Turbomachines, such as turbines, engines, and compressors, include pluralities of stationary vanes and rotating blades. These are typically arranged in alternating stacked airfoil rows disposed around and along the longitudinal axis of the machine, with the vanes affixed to the turbine casing and the blades affixed to a disk connected to a shaft. Efforts have been made to improve the efficiency of such machines by indexing or “clocking” the relative circumferential positions of airfoils in one row to the circumferential positions of airfoils in adjacent or nearby rows. Typically, such improvement is achieved by reducing the impact of vane wake on the rotating blades.
Some turbomachines, such as gas turbines, include a diffuser disposed adjacent the final stage of the turbine. Such a diffuser is configured to decelerate the exhaust flow, converting dynamic energy to a static pressure rise, and do so more efficiently when circumferential variation in the flow entering the diffuser is reduced. Known turbomachines and clocking methods do not address or consider the circumferential variation of the flow field entering the diffuser. In fact, some clocking methods may increase circumferential variation in order to provide efficiencies in other areas of the turbine, such as increased energy efficiency or decreased vibration and stress in the airfoils.